src: refactor to use locale functions

This makes the code more readable.

Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/39014


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>